Various methods are known in the art for optical three-dimensional (3D) mapping, i.e., generating a 3D profile of the surface of an object by processing an optical image of the object. This sort of 3D profile is also referred to as a depth map or depth image, and 3D mapping is also referred to as depth mapping. Some methods of 3D mapping are based on projecting patterned light onto the object, and then analyzing an image of the pattern on the object. The pattern may be random or quasi-random, or it may alternatively have a well-defined geometrical structure (commonly known as “structured light”).
One type of patterned light that may be used in depth mapping is a speckle pattern. For example, PCT International Publication WO 2007/043036, whose disclosure is incorporated herein by reference, describes a system and method for object reconstruction in which a coherent light source and a generator of a random speckle pattern project onto the object a coherent random speckle pattern. An imaging unit detects the light response of the illuminated region and generates image data. Shifts of the pattern in the image of the object relative to a reference image of the pattern are used in real-time reconstruction of a 3D map of the object. Further methods for 3D mapping using speckle patterns are described, for example, in PCT International Publication WO 2007/105205, whose disclosure is also incorporated herein by reference.
Other methods of optical 3D mapping project different sorts of patterns onto the object to be mapped. For example, PCT International Publication WO 2008/120217, whose disclosure is incorporated herein by reference, describes an illumination assembly for 3D mapping that includes a single transparency containing a fixed pattern of spots. A light source transilluminates the transparency with optical radiation so as to project the pattern onto an object. An image capture assembly captures an image of the pattern on the object, and the image is processed so as to reconstruct a 3D map of the object.
U.S. Patent Application Publication 2010/0007717, which is assigned to the assignee of the present patent application and whose disclosure is incorporated herein by reference, describes a device having a first input port for receiving color image data from a first image sensor and a second input port for receiving depth-related image data from a second image sensor. Processing circuitry generates depth maps using the depth-related image data, and then registers and synchronizes the depth maps with the color images.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.